Re: [ATM] Flex Rocker Question

["john sherman" <atm@mail.johnspics.com>]

Hi,

>The active area is not the bulls eye area but the fine
>darker strip at the bottom

Ah, yes. Their drawing shows it as a gray strip. But I found a "mechanical alignment" drawing at http://www.usdigital.com/products/em1-heds/ which shows it as a black and white strip (probably opaque and clear?). Also it does a good job of showing how the reader mounts. 

>If you want a reliable solution, you're close with the 
>strip linear encoder, _in principle_ .

Matt, thanks for giving all that great information. Yes, it appears that this strip will cost quite a bit. What would you suggest we do? Can we make strips using movie film or something? 


>I like your approach!

Thanks, but once again, I'm only repeating what I learned from this list in the first place. Also, thanks to Michael and all the folks who work behind the scenes to provide us with this fine list!

>How would you protect the strip against dust, 
>dew and mechanical damage? 

Ah, I haven't got there yet. I doubt if dew is a problem since the thing will be mounted under the scope where the ground can keep it warm. During an observing session there might not be enough dust build-up to matter, then always blow it clean before setting up. Mechanical alignment means as you move the scope around in AZ the encoder module stays aligned with the strip, this would require some well-made parts. Perhaps the module can have it's own little flex mount, so that it can "float" along the strip?

The EDivide is another interesting product they have listed, for those who want more resolution than 8+ feet of strip can give: 
http://www.usdigital.com/products/edivide/

John







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